Add a URL param to indicate group selection in Instant field trial.

chrome/browser/search_engines/template_url_service.cc

Index: chrome/browser/search_engines/template_url_service.cc
diff --git a/chrome/browser/search_engines/template_url_service.cc b/chrome/browser/search_engines/template_url_service.cc
index e60357bddb090a03ed32b8b64e33cff1e80d4127..09abd7e9f4a487d05e1b9e22df7cea8bf6859b4c 100644
--- a/chrome/browser/search_engines/template_url_service.cc
+++ b/chrome/browser/search_engines/template_url_service.cc
@@ -191,7 +191,7 @@ string16 TemplateURLService::CleanUserInputKeyword(const string16& keyword) {
 // static
 GURL TemplateURLService::GenerateSearchURL(const TemplateURL* t_url) {
   DCHECK(t_url);
-  UIThreadSearchTermsData search_terms_data;
+  UIThreadSearchTermsData search_terms_data(NULL);
   return GenerateSearchURLUsingTermsData(t_url, search_terms_data);
 }
 
@@ -735,7 +735,7 @@ void TemplateURLService::AddToMaps(const TemplateURL* template_url) {
   if (!template_url->keyword().empty())
     keyword_to_template_map_[template_url->keyword()] = template_url;
   if (loaded_) {
-    UIThreadSearchTermsData search_terms_data;
+    UIThreadSearchTermsData search_terms_data(NULL);
     provider_map_.Add(template_url, search_terms_data);
   }
 }
@@ -769,7 +769,7 @@ void TemplateURLService::SetTemplateURLs(
 void TemplateURLService::ChangeToLoadedState() {
   DCHECK(!loaded_);
 
-  UIThreadSearchTermsData search_terms_data;
+  UIThreadSearchTermsData search_terms_data(NULL);
   provider_map_.Init(template_urls_, search_terms_data);
   loaded_ = true;
 }
@@ -935,7 +935,7 @@ void TemplateURLService::UpdateNoNotify(const TemplateURL* existing_turl,
     keyword_to_template_map_.erase(existing_turl->keyword());
 
   // This call handles copying over the values (while retaining the id).
-  UIThreadSearchTermsData search_terms_data;
+  UIThreadSearchTermsData search_terms_data(NULL);
   provider_map_.Update(existing_turl, new_values, search_terms_data);
 
   if (!existing_turl->keyword().empty())
@@ -1088,7 +1088,7 @@ void TemplateURLService::GoogleBaseURLChanged() {
   }
 
   if (something_changed && loaded_) {
-    UIThreadSearchTermsData search_terms_data;
+    UIThreadSearchTermsData search_terms_data(NULL);
     provider_map_.UpdateGoogleBaseURLs(search_terms_data);
     NotifyObservers();
   }